2、Web开发

1、SpringMVC自动配置概览

2、功能简单分析

2.1、静态资源访问

（1）静态资源目录

类路径下：called /static (or /public or /resources or /META-INF/resources)
访问：当前项目路径/+静态资源名称

原理：静态映射/**
请求进来，先去找Controller看能不能处理。不能处理的所有请求又都交给静态资源处理器。静态资源找不到404

（2）静态资源访问前缀

默认无前缀
但是我们可以通过配置来修改前缀

spring.mvc.static-path-pattern=/res/**

（3）静态资源目录修改

可以指定到具体的自定义目录

spring.web.resources.static-locations=classpath:/file/

（4）Webjars技术

引入jar中的静态资源,自定映射jar包内容
https://www.webjars.org/

<dependency>
    <groupId>org.webjars</groupId>
    <artifactId>jquery</artifactId>
    <version>3.6.0</version>
</dependency>

访问：本项目路径+/webjars/….
示例：http://localhost:8080/webjars/jquery/3.6.0/jquery.js

2.2、欢迎页

创建一个index.html存放在静态资源目录下，就可以访问到欢迎页，假如配置了访问前缀就只能按全路径进行访问，不然可以通过https://localhost:8080直接进行访问。

2.3、favicon.ico

favicon.icon直接存放在静态资源路径下就可以。
但是不能配置静态资源路径

3.4、静态资源配置原理

• SpringBoot启动目录加载xxxAutoConfiguration类（自动配置类）

• SpringMVC自动配置基本都在WebMvcAutoConfiguration配置类、生效

  @Configuration(proxyBeanMethods = false)
  @ConditionalOnWebApplication(type = Type.SERVLET)
  @ConditionalOnClass({ Servlet.class, DispatcherServlet.class, WebMvcConfigurer.class })
  @ConditionalOnMissingBean(WebMvcConfigurationSupport.class)
  @AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE + 10)
  @AutoConfigureAfter({ DispatcherServletAutoConfiguration.class, TaskExecutionAutoConfiguration.class,
        ValidationAutoConfiguration.class })
  public class WebMvcAutoConfiguration {
  

• 给容器中配了什么

  @Configuration(proxyBeanMethods = false)
    @Import(EnableWebMvcConfiguration.class)
    @EnableConfigurationProperties({ WebMvcProperties.class,
            org.springframework.boot.autoconfigure.web.ResourceProperties.class, WebProperties.class })
    @Order(0)
    public static class WebMvcAutoConfigurationAdapter implements WebMvcConfigurer, ServletContextAware {
  

• 配置文件的相关属性和xxx进行了绑定。WebMvcProperties==spring.mvc、ResourceProperties==spring.resources、WebProperties==spring.web

• 只有一个有参构造器，所有参数都会从容器中找

  //ListableBeanFactory beanFactory 容器工厂
  //resourceHandlerRegistrationCustomizerProvider 资源处理器的自定义器
  //servletRegistrations 给应用注册Servlet、Filter
  public WebMvcAutoConfigurationAdapter(
                org.springframework.boot.autoconfigure.web.ResourceProperties resourceProperties,
                WebProperties webProperties, WebMvcProperties mvcProperties, ListableBeanFactory beanFactory,
                ObjectProvider<HttpMessageConverters> messageConvertersProvider,
                ObjectProvider<ResourceHandlerRegistrationCustomizer> resourceHandlerRegistrationCustomizerProvider,
                ObjectProvider<DispatcherServletPath> dispatcherServletPath,
                ObjectProvider<ServletRegistrationBean<?>> servletRegistrations) {
  

• 静态资源处理器

        @Override
        public void addResourceHandlers(ResourceHandlerRegistry registry) {
            if (!this.resourceProperties.isAddMappings()) {
                logger.debug("Default resource handling disabled");
                return;
            }
            addResourceHandler(registry, "/webjars/**", "classpath:/META-INF/resources/webjars/");
            addResourceHandler(registry, this.mvcProperties.getStaticPathPattern(), (registration) -> {
                registration.addResourceLocations(this.resourceProperties.getStaticLocations());
                if (this.servletContext != null) {
                    ServletContextResource resource = new ServletContextResource(this.servletContext, SERVLET_LOCATION);
                    registration.addResourceLocations(resource);
                }
            });
        }
  

• 可以通过addMapping配置禁用掉所有资源访问

  spring.web.resources.add-mappings=false
  

• 配置了默认的静态资源路径

    public static class Resources {
  
        private static final String[] CLASSPATH_RESOURCE_LOCATIONS = { "classpath:/META-INF/resources/",
                "classpath:/resources/", "classpath:/static/", "classpath:/public/" };
  
        /**
         * Locations of static resources. Defaults to classpath:[/META-INF/resources/,
         * /resources/, /static/, /public/].
         */
        private String[] staticLocations = CLASSPATH_RESOURCE_LOCATIONS;
  

• 欢迎页处理器源码规则

        @Bean
        public WelcomePageHandlerMapping welcomePageHandlerMapping(ApplicationContext applicationContext,
                FormattingConversionService mvcConversionService, ResourceUrlProvider mvcResourceUrlProvider) {
            WelcomePageHandlerMapping welcomePageHandlerMapping = new WelcomePageHandlerMapping(
                    new TemplateAvailabilityProviders(applicationContext), applicationContext, getWelcomePage(),
                    this.mvcProperties.getStaticPathPattern());
            welcomePageHandlerMapping.setInterceptors(getInterceptors(mvcConversionService, mvcResourceUrlProvider));
            welcomePageHandlerMapping.setCorsConfigurations(getCorsConfigurations());
            return welcomePageHandlerMapping;
        }
  

    WelcomePageHandlerMapping(TemplateAvailabilityProviders templateAvailabilityProviders,
            ApplicationContext applicationContext, Resource welcomePage, String staticPathPattern) {
        if (welcomePage != null && "/**".equals(staticPathPattern)) {
            logger.info("Adding welcome page: " + welcomePage);
            setRootViewName("forward:index.html");
        }
        else if (welcomeTemplateExists(templateAvailabilityProviders, applicationContext)) {
            logger.info("Adding welcome page template: index");
            setRootViewName("index");
        }
    }